Possible solution #4:
Install the new city water flange under the bathroom sink, where there is plenty of room. I confirmed with the Shurflo tech that this pump can self-prime up to 9
vertical feet. I'll need to measure a bit to confirm, but I think that will be enough priming power even with the pump under the kitchen sink. But if not, I can mount the pump under the bathroom sink as well, which is even more fun to work under than the kitchen sink.
Dave